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Ch 4 Functional anatomy of Bacteria and other Microbes Or The differences between Eukaryotic and Prokaryotic cells Q&A • Penicillin was called a “miracle drug” because it doesn’t harm human cells. Why doesn’t it? • Proks and euks are similar in chemical composition and reaction • Proks lack membrane bound organelles • Only Proks have peptidoglycan • Euks have membrane bound organelles • Euks have paired chromosomes • Euks have histones Nick sees the difference mainly in information and structural capacity • Proks lack membrane-enclosed organelles • Euks are like a 2mhz 100gb home computer • Proks are like a calculator • Human genome 4x109 • E. coli 4x106 The prokaryote • Unicellular • Multiply by binary fission • Differentiated by – – – – – – Morphology Chemical composition Nutritional requirements Biochemical activates Sources of energy Other tests Size • 0.2 to 2um in diameter • 2-8um in length • In biological systems there are always exceptions these are general sizes. Shape Shape • Coccus – Diplococci – Streptococci – Staphylococci • Bacillus • Spiral • Other pleomorphic shapes Basic components of a bacterial cell fig 4.6 Parts not seen • Glycocalyx – Capsule – Slime layer – Extracellular polysaccharide • Function • Toxicity • Protect from phagocytosis • Allow adherence • Reduce water loss • Collect nutrients Flagella: long filamentous appendages with filament, hook and basal body • Used in movement • Can present taxis – Negative – Positive • Monotrichous • Peritrichous • Flagellar H protein acts as an antigen E.c O157:H7 • Flagellin Flagella Arrangement Figure 4.7 Fimbriae/pili • Shorter and less complex than flagella • Helps adhere to surfaces • Used for sex and communication Cell wall • Major difference between eukaryotic and prok orgs. • Surrounds plasma membrane provides protection • Peptidoglycan – Polymer of • NAG • NAM • Short amino acid chain • Production inhibited by antibiotics • Prevents osmotic damage • Damage to cw is almost always lethal except Gram Positives have large cell wall and Teichoic acids Gram neg have lipopolysaccharide Peptidoglycan • Polymer of disaccharide: – Nacetylglucosamine (NAG) – N-acetylmuramic acid (NAM) Figure 4.12 Peptidoglycan in Gram-Positive Bacteria Figure 4.13a The Cell Wall • Prevents osmotic lysis • 4-7 Differentiate protoplast, spheroplast, and L form. • Made of peptidoglycan (in bacteria) • Linked by polypeptides Figure 4.6 Gram-Positive Bacterial Cell Wall Figure 4.13b Gram-Negative Bacterial Cell Wall Figure 4.13c Gram-positive Gram-positive Cell Wall Cell Wall Thin peptidoglycan • Thick peptidoglycan Outer membrane • Teichoic acids Periplasmic space Figure 4.13b–c Gram neg • Lipoprotein phospholipid outer membrane surrounding a thin peptidoglycan • Makes gram neg resistant to – Phagocytosis – Antibiotics – Chemical reactions – Enzymes (lysozyme) – Has lipid A endotoxin – O polysaccaride antigen O157:H7 E.c. Gram-Negative Outer Membrane Figure 4.13c How the gram stain works to differentiate between G+ and G- The Gram Stain (a) Gram-Positive (b) Gram-Negative Table 4.1 The Gram Stain Mechanism • Crystal violet-iodine crystals form in cell • Gram-positive – Alcohol dehydrates peptidoglycan – CV-I crystals do not leave • Gram-negative – Alcohol dissolves outer membrane and leaves holes in peptidoglycan – CV-I washes out Gram-Positive Gram-Negative Cell Wall Cell Wall 4-ring basal body • 2-ring basal body • Disrupted by lysozyme • Penicillin sensitive Endotoxin Tetracycline sensitive Figure 4.13b–c Nontypical cell walls • Mycoplasma (acid fast) do not have ppt containing cell wall. • Archaea contain another chemical called pseudomurein Atypical Cell Walls • Acid-fast cell walls – Like gram-positive – Waxy lipid (mycolic acid) bound to peptidoglycan – Mycobacterium – Nocardia Figure 24.8 Atypical Cell Walls • Mycoplasmas – Lack cell walls – Sterols in plasma membrane • Archaea – Wall-less or – Walls of pseudomurein (lack NAM and D-amino acids) Damage to the Cell Wall • • • • Lysozyme digests disaccharide in peptidoglycan Penicillin inhibits peptide bridges in peptidoglycan Protoplast is a wall-less cell Spheroplast is a wall-less gram-positive cell – Protoplasts and spheroplasts are susceptible to osmotic lysis • L forms are wall-less cells that swell into irregular shapes Plasma membrane • Defines the living and nonliving parts of the cell – Everything on the inside is living – Everything on the outside is not living • Is selectively permeable • Workspace for enzymes of metabolic reactions • • • • Plasma Membrane Phospholipid bilayer Peripheral proteins Integral proteins Transmembrane proteins Figure 4.14b PM Workspace – Nutrient breakdown – Energy production – Photosynthesis – Afforded by mesosomes which are regular infoldings of the plasma membrane • Weaknesses: destroyed by actions of alcohols, detergents and polymyxins Fluid Mosaic Model • Membrane is as viscous as olive oil. • Proteins move to function • Phospholipids rotate and move laterally Figure 4.14b Plasma Membrane • Damage to the membrane by alcohols, quaternary ammonium (detergents) and polymyxin antibiotics causes leakage of cell contents. Movement of Materials across Membranes • Simple diffusion: Movement of a solute from an area of high concentration to an area of low concentration Figure 4.17a Movement of Materials across Membranes • Facilitated diffusion: Solute combines with a transporter protein in the membrane Figure 4.17b-c Movement of Materials across Membranes ANIMATION Passive Transport: Special Types of Diffusion ANIMATION Passive Transport: Principles of Diffusion Movement of Materials across Membranes • Osmosis: The movement of water across a selectively permeable membrane from an area of high water to an area of lower water concentration • Osmotic pressure: The pressure needed to stop the movement of water across the membrane Figure 4.18a Movement of Materials across Membranes • Through lipid layer • Aquaporins (water channels) Figure 4.17d The Principle of Osmosis Figure 4.18a–b The Principle of Osmosis Figure 4.18c–e Movement of Materials across Membranes • Active transport: Requires a transporter protein and ATP • Group translocation: Requires a transporter protein and PEP ANIMATION Active Transport: Types ANIMATION Active Transport: Overview Cytoplasm's • The liquid component of the cell within the PM • Mostly water, dissolved ions, DNA ribosomes and inclusions • Concept of homeostasis Nuclear area • Contains the bacterial chromosome • Bacteria may also have plasmids with up to 25% of the genetic materials Ribosomes Figure 4.6a Ribosomes Figure 4.19 Inclusions • Typically reserve deposits of excess materials like inorganic phosphate • Polysaccharide granules • Lipids • Sulfur • Gas • iron The Prokaryotic Ribosome • Protein synthesis • 70S – 50S + 30S subunits Figure 4.19 Magnetosomes Figure 4.20 Inclusions • Metachromatic granules (volutin) • Polysaccharide granules • Lipid inclusions • Sulfur granules • Carboxysomes • Gas vacuoles • Magnetosomes • Phosphate reserves • • • • Energy reserves Energy reserves Energy reserves Ribulose 1,5-diphosphate carboxylase for CO2 fixation • Protein-covered cylinders • Iron oxide (destroys H2O2) Endospores • Resting and waiting stage • Resistant to drying and other harsh conditions The Eukaryotic cell Comparison • • • • Flagella and cilia tubulin (9/2) arrangement Cell wall of different materials Glycocalyx Plasma membrane organelles • • • • • • • • • Nucleus ER 80s ribosomes Golgi complex Lysozymes Vacuoles Mitochondria Chloroplasts Peroxisomes Organelles • • 4-18 Define organelle. 4-19 Describe the functions of the nucleus, endoplasmic reticulum, Golgi complex, lysosomes, vacuoles, mitochondria, chloroplasts, peroxisomes, and centrosomes. Organelles • Nucleus: Contains chromosomes • ER: Transport network • Golgi complex: Membrane formation and secretion • Lysosome: Digestive enzymes • Vacuole: Brings food into cells and provides support Organelles • Mitochondrion: Cellular respiration • Chloroplast: Photosynthesis • Peroxisome: Oxidation of fatty acids; destroys H2O2 • Centrosome: Consists of protein fibers and centrioles The Eukaryotic Nucleus Figure 4.24 The Eukaryotic Nucleus Figure 4.24a–b Rough Endoplasmic Reticulum Figure 4.25 Detailed Drawing of Endoplasmic Reticulum Figure 4.25a Micrograph of Endoplasmic Reticulum Figure 4.25b Golgi Complex Figure 4.26 Lysosomes and Vacuoles Figure 4.22b Mitochondria Figure 4.27 Chloroplasts Figure 4.28 Chloroplasts Figure 4.28a Chloroplasts Figure 4.28b Peroxisome and Centrosome Figure 4.22b Eukaryotic Cell • Not membrane-bound: – Ribosome – Centrosome and – Centriole Protein synthesis Consists of protein fibers centrioles Mitotic spindle formation Evolution of eukaryotes • Endosymbiotic theory Membrane activity • • • • • • Diffusion Osmosis Passive diffusion Facilitated diffusion Active transport Know the relationships Movement Across Membranes • Active transport of substances requires a transporter protein and ATP. • Group translocation of substances requires a transporter protein and PEP.